Pile guides are used on such structures as offshore jackets to properly align skirt piles, follower piles, and/or the hammer during the pile driving operation. In the case of closed pile guides, such follower and skirt piles can be preloaded onto the structure before it is launched which is a significant cost savings over having to load such elongated and unwieldly piles in the ocean. However, should additional lengths of the skirt pile be necessary or should more follower pile lengths be needed, the cost savings associated with preloading is consumed by the pains-taking process of threading these additional lengths through the closed guides. Open pile guides, on the other hand, are considerably easier to reload in the field but by being open, the cost savings of preloading onto the structure is not available.
Convertible-type pile guides which are closed through jacket launching and positioning and then opened prior to pile driving permit the advantages of preloaded piles to be combined with the advantages of open pile guides. Such convertible guides often are designed as hinged clamps that are held closed by bolts, hydraulically activated rams, or both. Clamps held closed only by bolts are less expensive to fabricate than hydraulic devices but they entail the expense of offshore divers when the time comes to remove these bolts. Hydraulically activated clamps reduce or eliminate the need for divers but their fabrication cost is very high. In the past, the high cost of bolted or hydraulic type convertible pile guides often offset the cost savings of combining preloaded pilings with the open pile guide method of pile installation.
It is thus an object of this invention to provide a pile guide that combines the cost savings of preloading with the ease of re-loading. Another object of this invention is to provide an inexpensive and reliable method of converting from a closed pile guide to an open pile guide.